The present invention relates to an agricultural ram press with which crop picked up from a cultivated field is pressed into bale form. Such a ram press is known from EP 1 769 674 B1, for example.
This conventional ram press comprises a bale chamber in which a ram is driven in an oscillating manner in order to compress the crop conveyed into the bale chamber into a bale. The crop reaches the bale chamber via a pick-up device which gathers the crop from the cultivated field, and a feed channel in which a feed rake moves. The feed rake performs two motions, specifically a gathering stroke, in which the feed rake is adjacent to the entrance of the feed channel and enters it and then moves only through a front region of the feed channel in order to pull crop—that has been freshly conveyed into the feed channel—away from the entrance and precompress it in a rear region of the feed channel to create space at the entrance for subsequently arriving crop, and a filling stroke, in which the feed rake moves from the entrance to an exit, and which conveys the crop gathered and precompressed in the feed channel out of the feed channel and into the bale chamber.
The feed rake comprises a two-arm feed rake lever which has agitator tines—which enter the feed channel—on the end of a first arm; the end of the second arm is hinge-mounted to a feed rake coupling rod, and a pivoting point between the two arms makes a motion on a circular trajectory, driven by an eccentric. An end of the coupling rod facing away from the feed rake lever is hinge-mounted to a feed rake control rod. When the feed rake control rod is at rest while the pivoting point of the feed rake lever moves along its circular trajectory, the joint that connects the coupling rod to the second arm of the feed rake lever moves on a circular arc, and the agitator tines make gathering-stroke motions on an elliptical trajectory that is elongated in the horizontal direction.
To control a filling stroke, the feed rake control rod is coupled via a piston rod to the drive of the baling ram and undergoes a swivel motion which causes the agitator tines to follow a sickel-like path.
In the ideal case, the agitator tines should enter the entrance of the feed rake channel at a steep angle, in both a gathering stroke and a filling stroke, and then move with minimal clearance from the bottom of the channel in order to capture all of the crop in the feed rake channel. At the end of a feed rake stroke, the agitator tines should exit the channel at a steep angle, wherein the exit point should be selected such that a precompressed crop body remains in the feed channel, the length of which corresponds exactly to the height of the bale chamber, thereby enabling it to evenly fill the entire cross section of the bale chamber when it is conveyed into it using a filling stroke. In a filling stroke, however, the tines should continue following the base of the chamber to the exit thereof, and then exit. It is difficult to fulfill these requirements in a satisfactory manner using the conventional drive mechanism. Since the feed rake control rod is moved continuously during the filling stroke, the trajectories of the agitator tines can coincide during the filling stroke and the gathering stroke only at points, although exact conformity of the trajectories in a front region of the feed rake channel would be extremely practical.